A　novel　application　of　a　nano-sized　titanium　dioxide　(TiO2)　photocatalyst　for　improving　the　performance　of　the　ceramic　insulator　under　contaminated　conditions　is　proposed　in　this　paper.　The　TiO2-coated　insulator　was　prepared　by　spraying　a　certain　amount　of　TiO2　sol　on　the　ceramic　insulator　followed　by　subsequent　calcination.　The　physical　and　chemical　properties　of　the　TiO2　film　were　studied　and　their　influences　on　the　self-cleaning　and　electrical　performances　of　the　ceramic　insulator　were　evaluated.　Compared　with　the　uncoated　insulators,　the　as-prepared　TiO2-coated　insulator　exhibited　an　enhanced　self-cleaning　ability　in　a　heavy　polluted　environment　because　of　the　excellent　photo-induced　catalytic　performance　of　the　TiO2　film.　Moreover,　the　TiO2-coated　insulators　presents　a　flashover　voltage　level　similar　to　normal　ceramic　insulators,　and　even　a　higher　performance　of　wet　flashover　than　the　latter.　It　was　proposed　that　the　semiconducting　property　and　the　hydrophilicity　of　TiO2　films　could　be　responsible　for　the　promoting　effect　on　the　electrical　performances　of　the　porcelain　insulator.　This　study　shows　that　coating　TiO2　films　on　the　surface　of　insulators　may　have　a　promise　in　preventing　pollution　flashover.